Multi-tubular chemical reactor with igniter for initiation of gas phase exothermic reactions

ABSTRACT

A multi-tubular chemical reactor includes an igniter for the initiation of gas phase exothermic reaction within the gas phase reaction zones of the tubular reactor units.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Division of and claims priority to priorapplication Ser. No. 15/033,997, filed May 3, 2016 and claims priorityto PCT/US2014/064238, filed Nov. 6, 2014, and also claims the benefit ofU.S. patent application Ser. Nos. 61/900,510 and 61/900,543, both filedNov. 6, 2013. The entire contents of each of these applications areincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present disclosure relates to chemical reactors and, moreparticularly, to multi-tubular chemical reactors incorporating ignitersfor initiation of gas phase exothermic reactions therein.

The teachings of the present disclosure, while generally applicable tomulti-tubular reactors of all types for conducting all manner of gasphase exothermic reactions, will be specifically exemplified herein bymulti-tubular reformers and methods of operating such reformers to bringabout the gas phase exothermic reforming of liquid and gaseousreformable fuels to produce hydrogen-rich reformates.

The conversion of a gaseous or vaporized liquid reformable fuel to ahydrogen-rich carbon monoxide-containing gas mixture, a product commonlyreferred to as “synthesis gas” or “syngas,” can be carried out inaccordance with any of such well known gas phase fuel reformingoperations as steam reforming, dry reforming, autothermal reforming andcatalytic partial oxidation (CPOX) reforming. Each of these fuelreforming operations has its distinctive chemistry and requirements andeach is marked by its advantages and disadvantages relative to theothers.

The development of improved fuel reformers, fuel reformer components,and reforming processes continues to be the focus of considerableresearch due to the potential of fuel cells, i.e., devices for theelectrochemical conversion of electrochemically oxidizable fuels suchhydrogen, mixtures of hydrogen and carbon monoxide, and the like, toelectricity, to play a greatly expanded role for general applicationsincluding main power units (MPUs) and auxiliary power units (APUs). Fuelcells also can be used for specialized applications, for example, ason-board electrical generating devices for electric vehicles, backuppower sources for residential-use devices, main power sources forleisure-use, outdoor and other power-consuming devices in out-of-gridlocations, and lighter weight, higher power density, ambienttemperature-independent replacements for portable battery packs.

Because large scale, economic production of hydrogen, infrastructurerequired for its distribution, and practical means for its storage(especially as a transportation fuel) are widely believed to be a longway off, much current research and development has been directed toimproving both fuel reformers as sources of electrochemically oxidizablefuels, notably mixtures of hydrogen and carbon monoxide, and fuel cellassemblies, commonly referred to as fuel cell “stacks,” as convertors ofsuch fuels to electricity, and the integration of fuel reformers andfuel cells into more compact, reliable and efficient devices for theproduction of electrical energy.

SUMMARY OF THE INVENTION

In accordance with the present disclosure, there is provided amulti-tubular chemical reactor comprising a plurality of spaced-apartreactor units, each reactor unit comprising an elongate tube having awall with internal and external surfaces, an inlet at one end and anoutlet at the opposing end, the wall enclosing a gaseous flow passagewayat least a portion of which defines a gas phase reaction zone, themulti-tubular chemical reactor can include at least one igniter forinitiation of a gas phase exothermic reaction within a gas phasereaction zone of a reactor unit. The igniter can include a radiantheat-producing element positioned in thermal communication with andproximity to, but in physical isolation from, the gas phase reactionzone.

With respect to the plurality of spaced-apart reactor units, the maximumdistance between adjacent reactor units can be that distance beyondwhich a gas phase exothermic reaction fails to be initiated in anadjacent reactor unit by the heat from a gas phase exothermic reactionin an operating reactor unit and/or during a steady-state mode ofoperation, the temperature of the plurality of spaced-apart reactorunits falls below a predetermined minimum array temperature. The minimumdistance between adjacent reactor units can be that distance below whichthe temperature at an outlet of a reactor unit is greater than apredetermined maximum temperature.

The multi-tubular chemical reactor can include at least one thermocoupledisposed within a chamber comprising the plurality of spaced-apartreactor units.

The multi-tubular chemical reactor can include a plurality of igniters.At least one igniter can be disposed at one end of a chamber comprisingthe plurality of spaced-apart reactor units and at least one igniterbeing disposed at the opposite end of the chamber. The multi-tubularchemical reactor can include a plurality of igniters and a plurality ofthermocouples disposed within a chamber comprising the plurality ofspaced-apart reactor units. At least one igniter and at least onethermocouple can be disposed at one end of the chamber and at least oneigniter and at least one thermocouple can be disposed at the oppositeend of the chamber.

The plurality of igniters and the plurality of thermocouples can bedisposed within the chamber such that at least one igniter at one end ofthe chamber can be opposite a thermocouple at the opposite end of thechamber.

The multi-tubular chemical reactor can include a source of gaseousreactants, the source of gaseous reactants in fluid communication withthe gas phase reaction zone(s) of the reactor unit(s).

The multi-tubular chemical reactor can include a controller forcontrolling the operation of the multi-tubular chemical reactor. Thecontroller can be in operative communication with the at least oneigniter, and if present, at least one of the at least one thermocoupleand the source of gaseous reactants.

In accordance with the present disclosure, there is provided a method ofcarrying out gas phase reforming exothermic reaction(s) within amulti-tubular chemical reactor to produce desired product(s). The methodgenerally includes introducing gaseous reactants into a reactor unit;initiating with radiant heat exothermic reforming reaction(s) of thegaseous reactants within a gas phase reaction zone of the reactor unit,thereby commencing the production of desired product(s); andtransferring heat produced by the exothermic reaction occurring withinthe gas phase reaction zone of the reactor unit to the gas phasereaction zone or one or more adjacent reactor units, thereby initiatingan exothermic reaction within at least one adjacent reactor unit untilin such manner an exothermic reaction has been initiated in each of theplurality of spaced-apart reactor units. The reactor unit can include aplurality of spaced-apart reactor units, each reactor unit can includean elongate tube having a wall with internal and external surfaces, aninlet at one end and an outlet at the opposing end, the wall enclosing agaseous flow passageway at least a portion of which defines a gas phasereaction zone.

The methods can include maintaining the exothermic reactions in theplurality of spaced-apart reactor units.

Maintaining the exothermic reactions can include introducing gaseousreactants into each reactor unit of the plurality of spaced-apartreactor units.

The exothermic reaction can be partial oxidation.

In some methods, initiating with radiant heat an exothermic reactioncomprises initiating at least one igniter comprising a radiantheat-producing element. The radiant heat-producing element can bepositioned in thermal communication with and proximity to, but inphysical isolation from, the gas phase reaction zone.

In accordance with the present disclosure, there is provided amulti-tubular chemical reactor comprising:

(a) a plurality of spaced-apart reactor units, each reactor unitcomprising an elongate tube having a wall with internal and externalsurfaces, an inlet at one end and an outlet at the opposing end, thewall enclosing a gaseous flow passageway at least a portion of whichdefines a gas phase reaction zone; and,

(b) at least one igniter for the initiation of gas phase exothermicreaction within the gas phase reaction zones of the reactor units, theigniter including a radiant heat-producing element positioned inproximity to, but in physical isolation from, exposed sections ofreactor units. The reactor units can be disposed within a chamber.Operation of the igniter can transmit radiant heat to an exposed sectionof at least one reactor unit in proximity thereto to initiate gas phaseexothermic reaction within the gas phase reaction zone thereof. Radiantheat produced by exothermic reaction occurring within the reaction zoneof the at least one reactor unit in turn can initiate exothermicreaction within at least one other reactor unit, optionally within achamber, until in such manner exothermic reaction has been initiated inall of the reactor units.

The igniter component of the multi-tubular gas phase chemical reactor,physically isolated as it can be from the exposed sections of reactorunits within the chamber, provides several benefits and advantages forthe management of reactor operation. Depending on the number andarrangement of tubular reactor units, a single igniter unit, and at mostonly a few igniter units, can often suffice to initiate, or light-off,exothermic gas phase reaction within the gas phase reaction zones of thereactor units. This simplifies both the construction of the reactor andits individual tubular reactor units, the operation of the reactor andthe identification and replacement of an inoperative or defectiveigniter should such be required.

Another major advantage of the igniter component of the reactor hereinis the ease with which it can be deactivated once steady-state operationof the reactor is achieved and reactivated to once again initiateexothermic gas phase reaction as the management of the reactoroperations require. The facility of activating and deactivating theigniter can be a benefit for multi-tubular reactors that in their normalfunctioning may undergo frequent and rapid on-off cycles.

BRIEF DESCRIPTION OF THE DRAWINGS

It should be understood that the drawings described below are forillustration purposes only. The drawings are not necessarily to scale,with emphasis generally being placed upon illustrating the principles ofthe present teachings. The drawings are not intended to limit the scopeof the present teachings in any way. Like numerals generally refer tolike parts.

FIG. 1 is schematic block diagram of an embodiment of gas phaseexothermic chemical reactor, specifically, a gaseous fuel CPOX reformer,in accordance with the present teachings.

FIG. 2 is a schematic block diagram of an exemplary control system formanaging the operation of the gaseous fuel CPOX reformer of FIG. 1.

FIG. 3 is a flowchart of an exemplary control routine executed by acontroller such as the control system illustrated in FIG. 2.

FIG. 4A is a longitudinal cross section view of an embodiment of agaseous fuel CPOX reformer in accordance with the present teachings.

FIG. 4B is a lateral (perpendicular to the longitudinal axis) crosssection view of the gaseous fuel CPOX reformer illustrated in FIG. 4A.

FIG. 4C is a plan cross section view of a portion of the gaseous fuelCPOX reformer illustrated in FIG. 4A.

FIG. 4D is a perspective view of a portion of the gaseous fuel CPOXreformer illustrated in FIG. 4A.

FIG. 5 is a longitudinal cross section view of another embodiment of gasphase chemical reactor, specifically, a liquid fuel CPOX reformer, inaccordance with the present teachings.

FIG. 6 is a flowchart of an exemplary control routing executed by acontroller for managing the operation of the liquid fuel CPOX reformerof FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that although the present description isdescribed as applying to a CPOX reformer, the present disclosure appliesto all exothermic reformers and/or reactions.

It is to be understood that the present teachings herein are not limitedto the particular procedures, materials and modifications described andas such can vary. It is also to be understood that the terminology usedis for purposes of describing particular embodiments only and is notintended to limit the scope of the present teachings which will belimited only by the appended claims.

For brevity, the discussion and description herein will mainly focus onpartial oxidation reforming reactions and reactants including catalyticpartial oxidation reforming reactions and reactants (a reformable fueland an oxygen-containing gas). However, the devices, assemblies, systemsand methods described herein can apply to other exothermic reformingreactions such as autothermal reforming and reactants (a reformablefuel, steam and an oxygen-containing gas) as well as other gas phaseexothermic reactions described herein. Accordingly, where anoxygen-containing gas is referenced herein in connection with a deviceor method, the present teachings should be considered as including steamin combination with an oxygen-containing gas unless explicitly statedotherwise or understood by the context. In addition, where a reformablefuel is referenced herein in connection with a device or method, thepresent teachings should be considered as including steam in combinationor alone, i.e., a reformable fuel and/or steam, unless explicitly statedotherwise or as understood by the context.

In addition, the reactors, systems and methods of the present teachingsshould be understood to be suitable to carry out CPOX reforming andautothermal reforming, for example, occurring within the same structureand components and/or with the same general methods as described herein.That is, the reactors, systems and methods of the present teachings candeliver the appropriate liquid reactants, for example, liquid reformablefuel and/or liquid water, from a liquid reformable fuel reservoir to avaporizer to create a vaporized liquid reformable fuel and steam,respectively, and the appropriate gaseous reactants, for example, atleast one of an oxygen-containing gas, a gaseous reformable fuel andsteam, from their respective sources to a desired component of a fuelcell unit or system for example, a reformer.

Where water is used in the delivery system, recycled heat from one ormore of a reformer, a fuel cell stack and an afterburner of a fuel cellunit or system can be used to vaporize the water to create steam, whichcan be present in the delivery system and/or introduced into thedelivery system from an independent source.

Throughout the specification and claims, where structures, devices,apparatus, compositions, etc., are described as having, including orcomprising specific components, or where methods are described ashaving, including or comprising specific method steps, it iscontemplated that such structures, devices, apparatus, compositions,etc., also consist essentially of, or consist of, the recited componentsand that such methods also consist essentially of, or consist of, therecited method steps.

In the specification and claims, where an element or component is saidto be included in and/or selected from a list of recited elements orcomponents, it should be understood that the element or component can beany one of the recited elements or components, or the element orcomponent can be selected from a group consisting of two or more of therecited elements or components. Further, it should be understood thatelements and/or features of a structure, device, apparatus orcomposition, or a method described herein, can be combined in a varietyof ways without departing from the focus and scope of the presentteachings whether explicit or implicit therein. For example, wherereference is made to a particular structure, that structure can be usedin various embodiments of the apparatus and/or method of the presentteachings.

The use of the terms “include,” “includes,” “including,” “have,” “has,”“having,” “contain,” “contains,” or “containing,” including grammaticalequivalents thereof, should be generally understood as open-ended andnon-limiting, for example, not excluding additional unrecited elementsor steps, unless otherwise specifically stated or understood from thecontext.

The use of the singular herein, for example, “a,” “an,” and “the,”includes the plural (and vice versa) unless specifically statedotherwise.

Where the use of the term “about” is before a quantitative value, thepresent teachings also include the specific quantitative value itself,unless specifically stated otherwise. As used herein, the term “about”refers to a ±10% variation from the nominal value unless otherwiseindicated or inferred.

It should be understood that the order of steps or order for performingcertain actions is immaterial so long as the present teachings remainoperable. For example, the methods described herein can be performed inany suitable order unless otherwise indicated herein or otherwiseclearly contradicted by context. Moreover, unless steps by their naturemust be conducted in sequence, they can be conducted simultaneously.

At various places in the present specification, numerical values aredisclosed as ranges of values. It is specifically intended that a rangeof numerical values disclosed herein include each and every value withinthe range and any subrange thereof. For example, a numerical valuewithin the range of from 0 to 20 is specifically intended toindividually disclose 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19 and 20 and any subrange thereof, for example, from 0to 10, from 8 to 16, from 16 to 20, etc.

The use of any and all examples, or exemplary language provided herein,for example, “such as,” is intended merely to better illuminate thepresent teachings and does not pose a limitation on the scope of theinvention unless claimed. No language in the specification should beconstrued as indicating any non-claimed element as essential to thepractice of the present teachings.

Terms and expressions indicating spatial orientation or attitude such as“upper,” “lower,” “top,” “bottom,” “horizontal,” “vertical,” and thelike, unless their contextual usage indicates otherwise, are to beunderstood herein as having no structural, functional or operationalsignificance and as merely reflecting the arbitrarily chosen orientationof the various views of reactors of the present teachings illustrated incertain of the accompanying figures.

As used herein, a “reformable fuel” refers to a liquid reformable fueland/or a gaseous reformable fuel.

The expression “gaseous reformable fuel” shall be understood to includereformable carbon- and hydrogen-containing fuels that are a gas at STPconditions, for example, methane, ethane, propane, butane, isobutane,ethylene, propylene, butylene, isobutylene, dimethyl ether, theirmixtures, such as natural gas and liquefied natural gas (LNG), which aremainly methane, and petroleum gas and liquefied petroleum gas (LPG),which are mainly propane or butane but include all mixtures made upprimarily of propane and butane, and ammonia, and the like, that whensubjected to reforming undergo conversion to hydrogen-rich reformates.

The expression “liquid reformable fuel” shall be understood to includereformable carbon- and hydrogen-containing fuels that are a liquid atstandard temperature and pressure (STP) conditions, for example,methanol, ethanol, naphtha, distillate, gasoline, kerosene, jet fuel,diesel, biodiesel, and the like, that when subjected to reformingundergo conversion to hydrogen-rich reformates. The expression “liquidreformable fuel” shall be further understood to include such fuelswhether they are in the liquid state or in the gaseous state, i.e., avapor.

As used herein, “gaseous reforming reaction mixture” refers to a mixtureincluding a gaseous liquid reformable fuel (e.g., a vaporized liquidreformable fuel), a gaseous reformable fuel or combinations thereof, andan oxygen-containing gas (e.g., air) and/or water (e.g., in the form ofsteam) in the case of autothermal reforming. A gaseous reformingreaction mixture can be subjected to a reforming reaction to create ahydrogen-rich product (“reformate”), which also can contain carbonmonoxide. Where a catalytic partial oxidation reforming reaction is tobe carried out, the gaseous reforming reaction mixture can be referredto a “gaseous CPOX reforming reaction mixture,” which includes areformable fuel and an oxygen-containing gas. Where an autothermalreforming reaction is to be carried out, the gaseous reforming reactionmixture can be referred to as a “gaseous AT reforming reaction mixture,”which includes a reformable fuel, an oxygen-containing gas and steam.

The term “reforming reaction” shall be understood to include theexothermic reaction(s) that occur during the conversion of a gaseousreaction medium to a hydrogen-rich reformate. The expression “reformingreaction” herein therefore includes, for example, CPOX and autothermalreforming.

Again, as stated previously for brevity, the discussion and descriptionherein will focus on partial oxidation reforming reactions and reactantsincluding catalytic partial oxidation reforming reactions and reactants(a reformable fuel and an oxygen-containing gas). However, the devices,assemblies, systems and methods described herein can equally apply toother reforming reactions such as autothermal reforming and theirrespective reactants. For example, for autothermal reforming, steam canbe introduced along with an oxygen-containing gas and/or a reformablefuel in the description herein.

The gas phase reactor of the disclosure will now be specificallydescribed in detail in connection with the embodiments of exemplarygaseous fuel CPOX reformers of FIGS. 1, 2, 3 and 4A-4D, and exemplaryliquid fuel CPOX reformer of FIGS. 5 and 6.

Gaseous fuel CPOX reformer 100 illustrated in the schematic blockdiagram of FIG. 1, exemplary control system 200 illustrated in theschematic block diagram of FIG. 2 for managing the operations ofreformer 100, the exemplary control routine illustrated in FIG. 3 forexecution by control system 200 of FIG. 2 and gaseous fuel CPOX reformer400 illustrated in FIGS. 4A-4D are of a kind disclosed in benefit U.S.patent application Ser. No. 61/900,543.

As shown in FIG. 1, gaseous fuel CPOX reformer 100 includes centrifugalblower 102 for introducing oxygen-containing gas, exemplified here andin the other embodiments of the present teachings by air, into conduit103, and for driving this and other gaseous streams (inclusive ofgaseous fuel-air mixture(s) and hydrogen-rich reformates) through thevarious passageways of the CPOX reformer. Conduit 103 can include flowmeter 104 and thermocouple 105. These and similar devices can be placedat various locations within a gaseous fuel CPOX reformer in order tomeasure, monitor and control the operation of the gaseous fuel CPOXreformer as more fully explained in connection with the control systemillustrated in FIG. 3.

In a start-up mode of operation of exemplary gaseous fuel CPOX reformer100, air introduced by blower 102 into conduit 103 combines with gaseousreformable fuel, exemplified here and in the other embodiments of thepresent teachings by propane, introduced into conduit 103 at arelatively low pressure from gaseous fuel storage tank 113 through fuelline 114 equipped with optional thermocouple 115, flow meter 116 andflow control valve 117. The air and propane combine in mixing zone 118of conduit 103. A mixer, for example, a static mixer such as in-linemixer 119, and/or vortex-creating helical grooves formed within theinternal surface of conduit 103, or an externally powered mixer (notshown), are disposed within mixing zone 118 of conduit 103 to provide amore uniform propane-air gaseous CPOX reaction mixture than wouldotherwise be the case.

The propane-air mixture (i.e., gaseous CPOX reaction mixture) entersmanifold, or plenum, 120 which distributes the reaction mixture to theinlets of tubular CPOX reactor units 109. In a start-up mode ofoperation of CPOX reformer 100, igniter 123, described in greater detailin connection with gaseous fuel CPOX reformer 400 of FIGS. 4A-4D,initiates the exothermic gaseous phase CPOX reaction of the gaseous CPOXreaction mixture within CPOX reaction zones 110 of tubular CPOX reactorunits 109 thereby commencing the production of hydrogen-rich reformate.Once steady-state CPOX reaction temperatures have been achieved (e.g.,150° C. to 1,100° C.), the exothermic reaction becomes self-sustainingand operation of the igniter can be discontinued. Thermocouple 125 ispositioned proximate to one or more CPOX reaction zones 110 to monitorthe temperature of the CPOX reaction occurring within CPOX reactor units109, the temperature measurement being relayed as a monitored parameterto reformer control system 126.

Reformer 100 can also include a source of electrical current, forexample, rechargeable lithium-ion battery system 127, to provide powerfor its electrically driven components such as blower 102, flow meters104 and 116, flow control valve 117 and igniter 123.

If desired, product effluent, for example, hydrogen-rich reformate, froma gaseous fuel CPOX reformer can be introduced into one or moreconventional or otherwise known carbon monoxide removal devices for thereduction of its carbon monoxide (CO) content, for example, where theproduct effluent is to be introduced as fuel to a fuel cell stackutilizing a catalyst that is particularly susceptible to poisoning byCO, for example, a polymer electrolyte membrane fuel cell. Thus, forexample, the product effluent can be introduced into a water gas shift(WGS) converter wherein CO is converted to carbon dioxide (CO₂) while atthe same time producing additional hydrogen, or the product effluent canbe introduced into a reactor wherein CO is made to undergo preferentialoxidation (PROX) to CO₂. CO reduction can also be carried out employinga combination of these processes, for example, WGS followed by PROX andvice versa. It is also within the scope of the present teachings toreduce the level of CO in the product reformate by passage of theproduct reformate through a known or conventional clean-up unit ordevice equipped with a hydrogen-selective membrane providing separationof the product reformate into a hydrogen stream and a CO-containingby-product stream. Units/devices of this kind can also be combined withone or more other CO-reduction units such as the aforementioned WGSconverter and/or PROX reactor.

Exemplary control system 200 illustrated in FIG. 2 is provided forcontrolling the operations of a gaseous fuel CPOX reformer in accordancewith the present teachings, e.g., reformer 100 of FIG. 1 and reformer400 of FIGS. 4A-4D. As those skilled in the art will readily recognize,with suitable modification to take into account the operations of theair-preheating and liquid fuel-vaporizing components of liquid fuel CPOXreformer 500 of FIG. 5, control system 200 can also be used forcontrolling the operations of this type of reformer as well.

As shown in FIG. 2, control system 200 includes controller 201 to managegaseous fuel CPOX reformer 202 in its start-up, steady-state, andshut-down modes of operation. The controller can be software operatingon a processor. However, it is within the scope of the present teachingsto employ a controller that is implemented with one or more digital oranalog circuits, or combinations thereof.

Control system 200 further includes a plurality of sensor assemblies,for example, thermocouple and associated fuel pressure meter 204,thermocouple and associated air pressure meter 209, and reformerthermocouple 214, in communication with controller 201 and adapted tomonitor selected operating parameters of CPOX reformer 202.

In response to input signals from the sensor assemblies, user commandsfrom a user-input device and/or programmed subroutines and commandsequences, controller 201 can manage the operations of a gaseous fuelCPOX reformer in accordance with the present teachings. Morespecifically, controller 201 can communicate with a controlsignal-receiving portion of the desired section or component of agaseous fuel CPOX reformer by sending command signals thereto directinga particular action. Thus, for example, in response to flow rate inputsignals from thermocouple and associated pressure meters 204 and 209and/or temperature input signals from reformer thermocouple 214,controller 201 can send control signals to fuel flow control valve 205,for example, to control the flow of fuel from gaseous fuel storage tank203 through fuel line 206 to conduit 207, to centrifugal blower 208 tocontrol the flow of air into conduit 207 and drive the flow of gaseousCPOX reaction mixture within and through CPOX reformer 202, to igniter211 to control its on-off states, and to battery/battery rechargersystem 212 to manage its functions.

The sensor assemblies, control signal-receiving devices andcommunication pathways herein can be of any suitable construction and ofthose known in the art. The sensor assemblies can include any suitablesensor devices for the operating parameters being monitored. Forexample, fuel flow rates can be monitored with any suitable flow meter,pressures can be monitored with any suitable pressure-sensing orpressure-regulating device, and the like. The sensor assemblies canalso, but do not necessarily, include a transducer in communication withthe controller. The communication pathways will ordinarily be wiredelectrical signals but any other suitable form of communication pathwaycan also be employed.

In FIG. 2, communication pathways are schematically illustrated assingle- or double-headed arrows. An arrow terminating at controller 201schematically represents an input signal such as the value of a measuredflow rate or measured temperature. An arrow extending from controller201 schematically represents a control signal sent to direct aresponsive action from the component at which the arrow terminates.Dual-headed pathways schematically represent that controller 201 notonly sends command signals to corresponding components of CPOX reformer202 to provide a determined responsive action, but also receivesoperating inputs from CPOX reformer 202 and mechanical units such asfuel control valve 205 and blower 208 and measurement inputs from sensorassemblies such as pressure meters 204 and 209 and thermocouple 214.

FIG. 3 presents a flow chart of an exemplary control routine that can beexecuted by a controller of a control system to automate the operationsof a gaseous fuel CPOX reformer, e.g., reformer 100 of FIG. 1 andreformer 400 of FIGS. 4A-4D. The flow chart can be executed by acontroller at a fixed interval, for example, every 10 milliseconds orso. The control logic illustrated in FIG. 3 performs several functionsincluding the management of gaseous flows and CPOX reaction temperaturesin start-up and steady-state modes of operation and management of theprocedure for the shut-down mode of reformer operation.

As shown in the various views of exemplary gaseous fuel CPOX reformer400 and components thereof illustrated in FIGS. 4A-4D, which arerepresentative of further embodiments of the present teachings, air asan oxygen-containing gas, typically at ambient temperature, isintroduced at a preset mass flow rate via centrifugal blower 402 throughinlet 403 of conduit 404. Propane is introduced into conduit 404 viafuel line 441 and fuel inlet 442. Propane and air begin to combine inmixing zone 420 of conduit 404 to provide a gaseous CPOX reactionmixture. A mixer of any suitable kind, for example, a static mixerdisposed within mixing zone 420 and/or a helically-grooved internal wallsurface of conduit 404, can be included to provide a gaseous CPOXreaction mixture of greater compositional uniformity than otherwisewould form in mixing zone 420.

Following its passage through the optional static mixer and/or contactwith helical grooves disposed within mixing zone 420, gaseous CPOXreaction mixture exits conduit 404 through outlet 425 and into fueldistribution manifold 426. From manifold 426, gaseous CPOX reactionmixture enters inlets 431 of CPOX reactor units 408 and into CPOXreaction zones 409 where the reaction mixture undergoes exothermic gasphase CPOX reaction to produce a hydrogen-rich, carbonmonoxide-containing reformate. In the start-up mode, one or moreigniters 435 initiates CPOX. After CPOX becomes self-sustaining, forexample, when the temperature of the reaction zone reaches from about250° C. to about 1100° C., igniter(s) 435 can be shut off as externalignition is no longer required to maintain the now self-sustainingexothermic CPOX reaction. Thermal insulation 410, for example, of themicroporous or alumina-based refractory type, surrounds those portionsof CPOX reformer 400 to reduce thermal losses from these components.

FIGS. 4A-4D illustrate an embodiment of the present teachings where twoigniters 435 (one for each separate array of CPOX reactor units 408) areused to initiate CPOX reaction within exothermic CPOX reaction zones 409of CPOX reactor units 408 disposed within and/or extending throughchamber 436 during the start-up mode of operation of reformer 400. Asshown in FIGS. 4C and 4D, CPOX reactor units 408 are arranged in twoseparate 2×7 parallel arrays with each array being disposed withinchamber 436, one such array flanking one side of conduit 404 and theother such array flanking the other side of conduit 404. The perimeterof an array marks the boundary between open space 438 of chamber 436 andthermal insulation 410. Exterior surfaces 437 of the walls of CPOXreactor units 408 corresponding to at least a portion of their CPOXreaction zones 409 are exposed within open space 438. Igniters 435 ofthe electrical resistance type, for example, rated at from 10 to 80watts or greater, are disposed at opposing ends of chamber 436 wheretheir radiant heat-producing elements 439 are positioned in proximityto, but in physical isolation from, exterior surfaces 437 of CPOXreactor units 408. Thermocouples 440 are disposed at the ends of chamber436 opposing igniters 435 in order to monitor the temperature of CPOXreaction zones 409 and provide a reformer control input as described inconnection with control system 200 illustrated in FIG. 2. Operation ofthe igniters causes radiant heat to be transferred to, and through, thewalls of one or more nearby CPOX reactor units whereby CPOX is initiatedwithin the CPOX reaction zone of such reactor unit(s). The thermalradiation emitted from the CPOX reaction zone(s) of these nearby CPOXreactor units can then initiate CPOX within the reaction zones of theremaining CPOX reactor units within the array as illustrated by the wavyarrows in FIG. 4C.

The provision of a single, or at most a few, igniter(s) 435 that avoiddirect contact with CPOX reactor units 408 provides several advantagesover a CPOX igniter system in which each CPOX reactor unit has its ownphysically attached or integrated igniter. Identification of aninoperative igniter can be problematic and its removal and replacementwithout damage to the CPOX reactor unit of which it is a part and/ordisturbance to other reactor units in the array can be difficult.Accordingly, a single or just a few igniters appropriately positionedwithin an array or plurality of CPOX reactor units can permit easy andsimple identification and extraction from CPOX reformer 400 of a failedor defective igniter, and its replacement with an operative igniter.

As shown in FIGS. 4C and 4D where two igniters are used to initiate theCPOX reaction within CPOX reaction zones 409 of CPOX reactor units 408,it can be advantageous to reverse the positions of igniter 435 andthermocouple 440 on one side of chamber 436 relative to the positions ofigniter 435 and thermocouple 440 on the other side of the chamber,particularly where there can be significant thermal communicationbetween the two chambers. Such an arrangement has been observed toresult in a more rapid initiation of CPOX within the CPOX reaction zonesof each separate array of CPOX reactor units. However, it should beunderstood that with appropriately dimensioned and positioned CPOXreactor units within a chamber, a single igniter can be used to initiateCPOX within the CPOX reaction zones of the CPOX reactor units within thechamber.

As those skilled in the art will readily recognize and appreciate, thecross sectional configuration, number and dimensions of CPOX reactorunits and the distances of their separation from each other measuredfrom their geometric centers, or centroids, will be made to depend onthe operational and mechanical performance specifications for aparticular gaseous fuel CPOX reactor. In the case of a CPOX reactor unitof substantially uniform circular cross section, for example, CPOXreactor unit 408 illustrated in FIGS. 4C and 4D, the number of such CPOXreactor units, their length and their internal and external diameters(defining the thickness of their gas-permeable walls) the gas-permeablewalls will be determined by, among other things, the hydrogen-producingcapacity of the CPOX reformer, which in turn is a function of severalfactors including the type, amount (loading and distribution of CPOXcatalyst within the gas-permeable walls), the characteristics of theporous structure of walls (characteristics influencing thegas-permeability of the walls and therefore affecting the CPOX reaction)such as pore volume (a function of pore size), the principal type ofpore (mostly open, i.e., reticulated, or mostly closed, i.e.,non-reticulated), and pore shape (spherical or irregular), thevolumetric flow rates of CPOX reaction mixture, CPOX temperature, backpressure, and the like.

The desired mechanical performance characteristics of a particulargaseous fuel CPOX reformer will depend to a considerable extent on suchfactors as the thermal and mechanical properties of the material usedfor construction of the CPOX reactor units, the volume and morphology ofthe pores of the gas-permeable structure of the walls of the CPOXreactor units, the dimensions of the reactor units, particularly wallthickness, and related factors.

For a gaseous fuel CPOX reformer to suitably function, the gaspermeability property of the catalytically active wall structure of atubular CPOX reactor unit enclosing a gaseous phase CPOX reaction zoneshould be such as to allow gaseous reformable fuel to enter freely anddiffuse through such wall structure thereby making effective contact notonly with surface CPOX catalyst but interior CPOX catalyst as well, ifpresent. It should be noted that CPOX reactor unit wall structureshaving limited gas permeability for the vaporized reformable fuel can bemass transport limited so as to impede significantly CPOX conversion ofthe gaseous reformable fuel to hydrogen-rich reformate. By contrast,catalytically active reactor wall structures of suitable gaspermeability promote CPOX conversion of the gaseous reformable fuel andselectivity for hydrogen-rich reformates of desirable composition.

Guided by the present teachings and employing known and conventionaltesting procedures, those skilled in the art can readily construct CPOXreactor units having catalytically active wall structures exhibitingoptimal gas permeability properties for a particular gaseous reformablefuel to be processed.

Materials from which the catalytically active wall structure of a CPOXreaction zone of a tubular CPOX reactor unit can be fabricated are thosethat enable such wall structures to remain stable under the hightemperatures and oxidative environments characteristic of CPOXreactions. Conventional and otherwise known refractory metals,refractory ceramics, and combinations thereof can be used for theconstruction of the catalytically active wall structure of a CPOXreaction zone. Some of these materials, for example, perovskites, canalso possess catalytic activity for partial oxidation and therefore canbe useful not only for the fabrication of the catalytically active wallstructure of a CPOX reaction zone but can also supply part or even allof the CPOX catalyst for such structure.

Among the useful refractory metals are titanium, vanadium, chromium,zirconium, molybdenum, rhodium, tungsten, nickel, iron and the like,their combinations with each other and/or with other metals and/or metalalloys, and the like. Refractory ceramics are an especially attractiveclass of materials for the construction of the catalytically active wallstructures due to their relatively low cost compared to many of therefractory metals and metal alloys that are also useful for thispurpose. The comparative ease with which such ceramics can be formedinto tubular gas-permeable structures of fairly reproducible pore typeemploying known and conventional pore-forming procedures and thegenerally highly satisfactory structural/mechanical properties ofceramics (including coefficients of thermal expansion and thermal shockperformance) and resistance to chemical degradation make themparticularly advantageous materials. Suitable refractory ceramics forthe construction of a CPOX reaction zone (which as previously stated,can include the entire wall structure of a CPOX reactor unit) include,for example, perovskites, spinels, magnesia, ceria, stabilized ceria,silica, titania, zirconia, stabilized zirconia such asalumina-stabilized zirconia, calcia-stabilized zirconia,ceria-stabilized zirconia, magnesia-stabilized zirconia,lanthana-stabilized zirconia and yttria-stabilized zirconia, zirconiastabilized alumina, pyrochlores, brownmillerites, zirconium phosphate,silicon carbide, yttrium aluminum garnet, alumina, alpha-alumina,gamma-alumina, beta-alumina, aluminum silicate, cordierite, MgAl₂O₄, andthe like, various ones of which are disclosed in U.S. Pat. Nos.6,402,989 and 7,070,752, the entire contents of which are incorporatedby reference herein; and, rare earth aluminates and rare earth gallatesvarious ones of which are disclosed in U.S. Pat. Nos. 7,001,867 and7,888,278, the entire contents of which are incorporated by referenceherein.

In general, the total or overall fuel conversion capacity of a CPOXreformer of a given design will be the sum of the fuel conversioncapabilities of its individual CPOX reactor units. The minimum distancebetween adjacent CPOX reactor units will be such that in thesteady-state mode of operation of the reformer, the temperature of thereactor units does not exceed a predetermined, or preset, maximum, andthe maximum distance between adjacent CPOX reactor units is thatdistance beyond which the CPOX reaction fails to be initiated within oneor more reactor units during a start-up mode of operation of the gaseousfuel CPOX reformer or the temperature within one or more CPOX reactorunits falls below a predetermined, or preset, minimum intended for thesteady-state mode of operation of the reformer. Within the aboveprinciples as guidance, the minimum and maximum distances betweenadjacent CPOX reactor units can be determined for a given reformerdesign employing routine testing methods.

More specifically, the maximum distance between adjacent CPOX reactorunits can be that distance beyond which a CPOX reaction fails to beinitiated within an adjacent CPOX reactor unit by the heat generatedfrom an initial CPOX reaction (e.g., an initial CPOX reaction initiatedby an igniter) in a first-ignited CPOX reactor unit or from a CPOXreaction in an operating CPOX reactor unit. The maximum distance can bethat distance beyond which, during a steady-state mode of operation, thetemperature of the array of spaced-apart CPOX reactor units falls belowa predetermined minimum array temperature. Depending on various factors,including those discussed herein, the predetermined minimum arraytemperature of an array of spaced-apart CPOX reactor units duringsteady-state mode of operation can be about 550° C., about 575° C.,about 600° C., about 625° C., about 650° C., about 675° C., about 700°C., about 725° C., about 750° C., about 775° C., about 800° C., about825° C., or about 850° C.

The minimum distance between adjacent CPOX reactor units can be thatdistance below which the temperature at an outlet of a CPOX reactor unitis greater than a predetermined maximum temperature. The predeterminedmaximum temperature can be a temperature that is tolerable by an inletof a fuel cell stack in thermal and fluid communication with an outletof a CPOX reactor unit, for example, a temperature at which the seals ofthe inlets of the fuel cell stack do not degrade and remain functional.Depending on various factors, including those discussed herein, thepredetermined maximum temperature of a CPOX reactor unit can be about775° C., about 800° C., about 825° C., about 850° C., about 875° C.,about 900° C., about 925° C., about 950° C., about 975° C., or about1000° C.

The present teachings contemplate the use of any of the heretofore knownand conventional CPOX catalysts (including catalyst systems), methods ofincorporating catalyst within a porous substrate or support,specifically, the gas-permeable wall of the CPOX reactor unit, andpatterns of catalyst distribution including, but not limited to,catalyst confined to a particular section of a wall, catalyst loadingincreased along the length of a reactor unit and/or decreased from aninner surface of a wall to its outer surface, CPOX catalyst that variesin composition along the length of the reactor unit, and similarvariants. Thus, for example, increasing catalyst loading within a wallof a CPOX reactor unit from the start of a CPOX reaction zone to, ornear, the end thereof can be helpful in maintaining a constant CPOXreaction temperature within this zone.

Among the many known and conventional CPOX catalysts that can beutilized herein are the metals, metal alloys, metal oxides, mixed metaloxides, perovskites, pyrochlores, their mixtures and combinations,including various ones of which are disclosed, for example, in U.S. Pat.Nos. 5,149,156; 5,447,705; 6,379,586; 6,402,989; 6,458,334; 6,488,907;6,702,960; 6,726,853; 6,878,667; 7,070,752; 7,090,826; 7,328,691;7,585,810; 7,888,278; 8,062,800; and, 8,241,600, the entire contents ofwhich are incorporated by reference herein.

While numerous highly active noble metal-containing CPOX catalysts areknown and as such can be useful herein, they are generally less oftenemployed than other known types of CPOX catalysts due to their highcost, their tendency to sinter at high temperatures and consequentlyundergo a reduction in catalytic activity, and their proneness topoisoning by sulfur.

Perovskite catalysts are a class of CPOX catalyst useful in the presentteachings as they are also suitable for the construction of thecatalytically active wall structures of a CPOX reactor unit. Perovskitecatalysts are characterized by the structure ABX₃ where “A” and “B” arecations of very different sizes and “X” is an anion, generally oxygen,that bonds to both cations. Examples of suitable perovskite CPOXcatalysts include LaNiO₃, LaCoO₃, LaCrO₃, LaFeO₃ and LaMnO₃.

A-site modification of the perovskites generally affects their thermalstability while B-site modification generally affects their catalyticactivity. Perovskites can be tailor-modified for particular CPOXreaction conditions by doping at their A and/or B sites. Doping resultsin the atomic level dispersion of the active dopant within theperovskite lattice thereby inhibiting degradations in their catalyticperformance. Perovskites can also exhibit excellent tolerance to sulfurat high temperatures characteristic of CPOX reforming. Examples of dopedperovskites useful as CPOX catalysts include La_(1-x)Ce_(x)FeO₃,LaCr_(1-y)Ru_(y)O₃, La_(1-x)Sr_(x)Al_(1-y)Ru_(y)O₃ andLa_(1-x)Sr_(x)FeO₃ wherein x and y are numbers ranging, for example,from 0.01 to 0.5, for example, from 0.05 to 0.2, etc., depending on thesolubility limit and cost of the dopants.

Liquid fuel CPOX reformer 500 illustrated in FIG. 5 and the exemplarycontrol routine illustrated in FIG. 6 for the automated operation ofreformer 500 are of a kind disclosed in benefit U.S. patent applicationSer. No. 61/900,510.

As shown in exemplary liquid fuel CPOX reformer 500 of FIG. 5 which isfurther representative of the present teachings, air as anoxygen-containing gas is introduced at ambient temperature and at apreset mass flow rate via centrifugal blower 502 through inlet 503 ofconduit 504, which includes a generally U-shaped conduit sectionfavoring compact design. The ambient temperature air is initially heatedin the start-up mode operation of the reformer to within a preset rangeof elevated temperature by passage through first heating zone 505supplied with heat from electric heater 506 which can be of aconventional or otherwise known electrical resistance type rated, forexample, at from 10 to 80 watts or even greater depending upon designedrange of fuel processing capacity of reformer 500. Electrical resistanceheaters are capable of raising the temperature of ambient air introducedinto a conduit to a desired level for a relatively wide range of CPOXreformer configurations and operating capacities. During thesteady-state mode of operation of reformer 500, electric heater 506 canbe shut off, the air introduced into conduit 504 then being initiallyheated within second heating zone 507 by heat of exotherm recovered fromCPOX reaction zones 509 of elongate tubular gas-permeable CPOX reactorunits 508, for example, of the structure and composition described abovein connection with CPOX reactor units 408 of gaseous fuel CPOX reformer400 of FIGS. 4A-4D. In this manner, the temperature of the airintroduced into conduit 504 can be increased from ambient to within somepreset elevated range of temperature with the particular temperaturebeing influenced by a variety of design, i.e., structural andoperational, factors as those skilled in the art will readily recognize.

As in the case of gaseous fuel CPOX reformer 400 of FIGS. 4A-4D, thermalinsulation 510 advantageously surrounds heat-radiating portions ofliquid fuel CPOX reformer 500 in order to reduce thermal lossestherefrom.

To raise the temperature of the air that had been initially heated bypassage through first heating zone 505 in a start-up mode or throughsecond heat zone 507 in a steady-state mode, as the initially heated aircontinues to flow downstream in conduit 504, it advantageously flowsthrough optional third heating zone 512 supplied with heat from optionalsecond electric heater unit 513. Because optional second electric heaterunit 513 need only increase the temperature of the initially heated airby a relatively small extent, it can function as an incremental heatercapable of making the typically small adjustments in air temperaturethat are conducive to precise and rapid thermal management of thereformer both with regard to the functioning of its fuel vaporizationsystem and its tubular CPOX reactor units.

A liquid reformable fuel such as any of those mentioned above, andexemplified in this and the other embodiments of the present teachingsby automotive diesel, is introduced via fuel line 514 terminating withinconduit 504 in liquid fuel spreader device 515, for example, a wick (asshown) or spray device.

Any conventional or otherwise known pump or equivalent device 518 forpassing fluid through the passageways and conduits of a liquid fuel CPOXreformer, for example, for introducing liquid fuel through fuel line 514into conduit 504, can be used. For example, a metering pump, rotarypump, impeller pump, diaphragm pump, peristaltic pump, positivedisplacement pump such as a gerotor, gear pump, piezoelectric pump,electrokinetic pump, electroosmotic pump, capillary pump, and the like,can be utilized for this purpose. In some embodiments, pump orequivalent device 518 can deliver the fuel on an intermittent or pulsedflow basis. In certain embodiments, a pump or equivalent device candeliver the fuel as a substantially continuous flow. In particularembodiments, a pump or equivalent device can make rapid adjustments infuel flow rate in response to changing CPOX reformer operatingrequirements.

As indicated above, the pressurized liquid fuel can be spread within aconduit by a wick or as a fine spray or otherwise in droplet form by anyof such conventional or otherwise known spray devices as fuel injectors,pressurized nozzles, atomizers (including those of the ultrasonic type),nebulizers, and the like.

Heat produced by electric heater 506 within first heating zone 505 in astart-up mode or heat of exotherm recovered from CPOX within secondheating zone 507 during a steady-state mode, combined, if desired, withheat produced by optional second electric heater 513 within optionalheating zone 512 function in unison to vaporize the liquid fuelintroduced into conduit 504 and together constitute the principalcomponents of the fuel vaporizer system of the reformer.

Optional second electric heater 513 operates to not only incrementallyraise the temperature of the initially heated ambient temperature airpassing within its associated optional third heating zone but can alsobe used to heat the liquid fuel prior to its introduction into conduit504 thereby facilitating the vaporization of the fuel once it enters theconduit.

To provide for the heating of the liquid fuel before it enters mainconduit 504, fuel line 514 traverses the wall of conduit 504 withsection 519 of the fuel line being extended in length to prolong theresidence time of fuel flowing therein where the fuel line passesthrough, or is proximate to, optional third heating zone 512 of mainconduit 504. An extended fuel line section can assume a variety ofconfigurations for this purpose, for example, a coiled or helicalwinding (as shown) or a series of lengthwise folds, disposed on orproximate to the exterior surface of a conduit corresponding to a secondheating zone or any similar such configuration disposed within theinterior of the conduit at or near the second heating zone. Regardlessof its exact configuration and/or disposition, extended fuel linesection 519 must be in effective heat transfer proximity to optionalthird heating zone 512 so as to receive an amount of heat sufficient toraise the temperature of the fuel therein to within some preset range oftemperature. Thus, a portion of the thermal output of optional secondelectric heater 513 within third heating zone 512 of conduit 504, inaddition to further heating air flowing within this zone, will transferto fuel, for example, diesel fuel, flowing within the distal section 519of fuel line 514, which distal section of fuel line 514 can belengthened or extended as shown by reference numeral 519, therebyraising its temperature to within the preset range. Whichever range oftemperature values is chosen for the fuel within the fuel line, itshould not exceed the boiling point of the fuel (from 150° C. to 350° C.in the case of diesel) if vapor lock and consequent shut-down ofreformer 500 are to be avoided.

Liquid fuel spreader 515 is disposed within conduit 504 downstream fromoptional second heating zone 512 and associated optional second electricheater 513 and upstream from mixing zone 520. Thermocouple 522 disposedwithin chamber 536 and thermocouple 523 is disposed within mixing zone520 monitor, respectively, the temperatures of CPOX reforming occurringwithin CPOX reaction zones 509 of CPOX reactor units 508 and thetemperature of the vaporized fuel-air mixture.

In the liquid fuel vaporizer systems described herein, there is no or atmost little opportunity for the diesel to come into direct contact witha heated surface, for example, that of an electrical resistance heaterelement, that would pose a risk of raising the temperature of the dieselfuel to or above its flash point, to cause spattering of the fuel ratherthan its vaporization and/or cause pyrolysis of the fuel resulting incoke formation. Thus, the temperature of the diesel fuel can be readilyand reliably maintained at a level below its flash point and withoutsignificant incidents of spattering or coking.

Following its passage through static mixer 521 disposed within mixingzone 520, gaseous CPOX reaction mixture exits main conduit 504 throughoutlet 525 and enters manifold 526. From manifold 526, the gaseous CPOXreaction mixture enters tubular CPOX reactor units 508 through inlets531. The gaseous CPOX reaction mixture then enters CPOX reaction zones509 where the mixture undergoes gaseous phase CPOX reaction(s) toproduce a hydrogen-rich, carbon monoxide-containing reformate. In thestart-up mode, at least one igniter 535, the heat-radiating element ofwhich is disposed within chamber 536, is activated thereupon initiatingCPOX. Igniter 535 and its operation are essentially identical to igniter435 of gaseous fuel CPOX reformer 400 and the latter's operation. AfterCPOX becomes self-sustaining, for example, when the temperature ofreaction zone 509 reaches from about 250° C. to about 1100° C.,igniter(s) 535 can be shut off as external ignition is no longerrequired to maintain the now self-sustaining exothermic CPOX reaction.

Further in accordance with the present teachings, steam can beintroduced into the reformer so that the reformer may be operated tocarry out autothermal and/or steam reforming reaction(s).

In one embodiment, the reformer can be initially operated to performCPOX conversion of a liquid or gaseous reformable fuel thereby providingheat of exotherm that, with or without additional heat, for example,supplied by an electric heater, can be recovered to produce steam in asteam generator. The thus-generated steam can be introduced into thereformer in one or more locations therein. One suitable location is theevaporator where the steam can provide heat to vaporize liquid fuel. Forexample, steam introduced into wick 515 in reformer 500 illustrated inFIG. 5 can provide heat for vaporizing liquid fuel on wick surfaces atthe same time helping to eliminate or suppress clogging of suchsurfaces.

In another embodiment, a reformer in accordance with the presentteachings can be connected to a fuel cell stack in which hydrogen-richreformate from the reformer is converted to electrical current.Operation of the fuel cell stack, and where present an associatedafterburner unit, can provide source(s) of waste heat that can berecovered and utilized for the operation of a steam generator, again,with or without additional heat such as that supplied by an electricheater. The steam from the steam generator can then be introduced intothe reformer, for example, through wick 515 of reformer 500 of FIG. 5,to support autothermal or steam reforming. In this arrangement ofintegrated reformer and fuel cell stack, the source(s) of waste heatreferred to can supply the necessary heat to drive endothermicreaction(s) that are involved in autothermal and steam reformingprocesses.

In sum, it should be understood that the delivery systems of the presentteachings can deliver the appropriate reactants for carrying outreforming reactions including partial oxidation (“POX”) reforming suchas catalytic partial oxidation (“CPOX”) reforming, steam reforming, andautothermal (“AT”) reforming. The liquid reactants such as liquidreformable fuels and water can be delivered from and through the “liquidreformable fuel” delivery components, conduits, and assemblies of thedelivery system. The gaseous reactants such as gaseous reformable fuels,steam, and an oxygen-containing gas such as air can be delivered fromand through the “gaseous reformable fuel” delivery components, conduits,and assemblies of the delivery system. Certain gaseous reactants such assteam and an oxygen-containing gas can be delivered from and throughcomponents and assemblies that are peripheral or secondary to thedelivery systems of the present teachings, for example, anoxygen-containing gas can be delivered from a source ofoxygen-containing gas that is independently in operable fluidcommunication with at least one of a vaporizer, a reformer, and a fuelcell stack of a fuel cell unit or system, for example, to mix with aliquid reformable fuel and/or a vaporized liquid reformable fuel priorto reforming.

The present teachings encompass embodiments in other specific formswithout departing from the spirit or essential characteristics thereof.The foregoing embodiments are therefore to be considered in all respectsillustrative rather than limiting on the present teachings describedherein. Scope of the present invention is thus indicated by the appendedclaims rather than by the foregoing description, and all changes thatcome within the meaning and range of equivalency of the claims areintended to be embraced therein.

The invention claimed is:
 1. A method of carrying out a gas phaseexothermic reaction within a multi-tubular chemical reactor to producedesired product(s), the method comprising: introducing gaseous reactantsinto an inlet of a gaseous flow passageway of a plurality of reactorunits, each reactor unit of the plurality comprising an elongate tubehaving a wall with an internal surface, an external surfaces, and a wallinterior between the internal and external surfaces, at least a portionof the wall interior adapted to function as a gas phase reaction zone,the interior surface of the wall enclosing the gaseous flow passagewayhaving the inlet at one end and an outlet at the opposing end, theinterior surface of the wall adapted to permit gas flowing through thepassageway to enter the wall interior at the gas phase reaction zone;flowing at least a portion of the gaseous reactants into the gas phasereaction zones of the plurality of reactor units; initiating withradiant heat an exothermic reaction of the gaseous reactants within thegas phase reaction zone of at least one of the reactor units, therebycommencing the production of desired product(s) and exothermic heat; andtransferring heat produced by the exothermic reaction occurring withinthe gas phase reaction zone of the at least one reactor unit to the gasphase reaction zone of one or more adjacent reactor units, therebyinitiating an exothermic reaction within the at least one adjacentreactor unit until in such manner an exothermic reaction has beeninitiated in each of the plurality of spaced-apart reactor units.
 2. Themethod of claim 1, wherein the initiating of the exothermic reaction inthe at least one reactor unit comprises heating the at least one reactorunit with at least one igniter, the igniter comprising a radiantheat-producing element, wherein the radiant heat-producing element ispositioned in thermal communication with and proximity to, but inphysical isolation from, the gas phase reaction zone.
 3. The method ofclaim 1 comprising maintaining the exothermic reactions in the pluralityof spaced-apart reactor units with the exothermic heat of the reactionsin the plurality of reactor units.
 4. The method of claim 1 wherein theexothermic reaction is catalytic partial oxidation.
 5. The method ofclaim 1, wherein the distance between adjacent reactor units is no morethan the distance beyond which the exothermic reaction fails to beinitiated in the adjacent reactor unit by the exothermic heat from theat least one adjacent reactor unit in which the exothermic reaction isoccurring.
 6. The method of claim 1, comprising establishing apredetermined minimum array temperature value, and setting the maximumdistance between adjacent reactor units as the distance at which thetemperature of the plurality of spaced-apart reactor units falls belowthe predetermined minimum array temperature value.
 7. The method ofclaim 1, comprising establishing a predetermined maximum temperaturevalue, and setting the minimum distance between adjacent reactor unitsas the distance below which the temperature at an outlet of the gaseousflow passageway is greater than the predetermined maximum temperaturevalue.
 8. The method of claim 1, wherein the exothermic reaction isautothermal reforming.
 9. The method of claim 1, wherein the reactorunits are within a chamber, and measuring the temperature within thechamber with a thermocouple.
 10. The method of claim 1, wherein theexothermic reaction is initiated in multiple reactor units with multipleradiant heat electric igniters.
 11. The method of claim 1, wherein aplurality of electric radiant heat igniters, the plurality or reactorunits and a plurality of thermocouples are all disposed within aninsulated chamber, with one igniter at one end of the chamber opposite athermocouple at the opposite end of the chamber.
 12. The method of claim1, wherein the reactants of the exothermic reaction are fed into aconduit and mixed together and the mixed reactants are fed from theconduit into the inlet.
 13. The method of claim 12, wherein thereactants are gaseous fuel and air and mixing is performed with a staticmixer within the conduit.
 14. The method of claim 1, comprising using acontroller to control the operation of the multi-tubular chemicalreactor, the controller in operative communication with at least oneelectric radiant heat igniter, at least one one thermocouple and asource of the gaseous reactants.
 15. The method of claim 1, wherein thegaseous reactants comprise methane, butane, or propane.
 16. The methodof claim 1, wherein the gaseous reactants comprise vaporized dieselfuel, gasoline or kerosene.